So I am fully aware that the likelihood of this issue being seen and actually worked on is slim to none, but I still feel I should report it anyway. I noticed the PlayWnd compiled executable exhibits some very strange behavior. While I was browsing through the project's code, I discovered that the sample provides the user two options for opening media in the player: 1) open media using the openfiledialog control, or 2) pass the media file as an argument to the player executable via command line. Media that is opened using the first method opens perfectly without issue. However, attempting to open the exact same media using the latter method (pass the npath to the media file as a command line argument) results in the file being loaded (as I can still hear the audio from the media file), but absolutely no video. very wierd.
Have you tried tracing the code? Looks like there's some things in UpdateMainTitle that might be related, and using a command line affects how and when that's called.